Efficacy of In Vitro Addition of Low‐Dose Arachidonic Acid in Improving the Sperm Motility of Obese Infertile Men With Asthenozoospermia

This study aimed to investigate the impact of in vitro low-dose arachidonic acid (AA) addition on enhancing sperm motility in obese infertile men with asthenozoospermia. Semen samples were collected from 115 infertile men, categorized into two BMI groups: 18.5-23.9 kg/m² and ≥ 28 kg/m², with all subjects demonstrating a sperm concentration of ≥ 15 × 10⁶/mL. These were further divided into four cohorts based on the percentage of sperm progressive motility (PR): control-normal, control-asthenozoospermia, obese-normal, and obese-asthenozoospermia. Normal PR was classified as ≥ 32%, while asthenozoospermia was characterized by PR < 32%. Metabolomic analysis was employed to quantify seminal plasma metabolites, with differential metabolites identified through statistical evaluation. Additionally, semen samples from 10 infertile men-5 with a body mass index (BMI) of 18.5-23.9 kg/m² and 5 with a BMI of ≥ 28 kg/m²-underwent further scrutiny. Post-initial semen analysis, 1 mL of semen stock was extracted, treated with 100 pg of AA, incubated at 37°C for 1 h, and reanalyzed to determine the impact on sperm motility. Additionally, 16 Sprague Dawley (SD) rats were split into two groups: control and obese. The control group received a standard diet, while the obese group was subjected to a 45% high-fat diet. After 3 months, the rats were euthanized via cervical dislocation, and their prostate and seminal vesicles were collected for metabolite analysis. A comprehensive analysis of 4635 metabolites in seminal plasma revealed that bile acid secretion emerged as the most significant pathway within the organic systems category, accounting for 0.6% of the total metabolites. Meanwhile, metabolic pathways overwhelmingly dominated the metabolism category, with AA metabolism contributing 4.62%. Notably, 29 metabolites were associated with bile acid secretion, yet no significant differences were observed between the PR ≥ 32% and < 32% groups. In contrast, 214 metabolites were linked to AA metabolism, exhibiting a predominantly downregulated trend, with no upregulated metabolites identified. Within the seminal plasma AA metabolic network, indicators showed a positive association with the induced acrosome reaction, seminal plasma Ca²⁺ levels, PR, and the proportion of grade A sperm (rapid forward motion, speed ≥ 25 μm/s). Additionally, secretory phospholipase A2 (sPLA2), AA, and cyclooxygenase-1 (COX1) levels demonstrated a negative correlation with anthropometric measurement parameters in the Control-SP group, though this correlation did not reach statistical significance, while a positive correlation was evident in the Obesity-SP group. The concentrations of sPLA2, AA, and COX1 within the AA metabolic network exhibited the following trend: Control-SP-N > Obesity-SP-N > Control-SP-A > Obesity-SP-A. In vitro addition of 100 pg AA significantly enhanced the proportion of grade B sperm (slow-moving, speed < 25 μm/s) while reducing grade C sperm (non-forward-moving) in individuals with a BMI of 18.5-23.9 kg/m² (p < 0.05). In contrast, for those with a BMI ≥ 28 kg/m², a marked increase in grade A and grade B sperm and a corresponding reduction in grade C sperm was noted (p < 0.05). Human seminal plasma levels of sPLA2, AA, and COX1 were significantly elevated in the Control-SP group compared to the Obesity-SP group (p < 0.05). However, sPLA2, AA, and COX1 levels in the prostate and seminal vesicle of SD rats did not differ significantly between the Control and Obesity groups (p > 0.05). Distinct metabolic profiles in seminal plasma of infertile men, stratified by BMI, exhibit significant impacts on sperm quality. Low-dose AA, under physiological conditions, maintains sperm integrity and augments fertilization potential. In vitro administration of low-dose AA demonstrates superior effectiveness in enhancing sperm parameters, particularly in obese individuals with asthenozoospermia.